Should I be using 85 or 87 octane in Colorado?

In Colorado, 85 is the regular gas, but due to the higher elevation, it’s mixed to behave like 87 octane. Kia recommends 87, but in Colorado, that’s mid-grade and almost 40 cents more expensive per gallon. Is there a problem using 85 instead of 87 in Colorado? What do people here think is the right choice for gas in Colorado?

I’ve been using 85 for over 50,000 miles with no issues.

I use 85 here in Colorado because 87 isn’t common. I haven’t had any issues compared to using 91, which is the other common type here. I only get gas at Costco because it’s a lot cheaper than at regular stations.

Edit: I’ve been using 85 for two years. When I leave Colorado, I use 87. I usually go out of state once a year for a couple of weeks.

@TurboTraveler
Costco gas is great.

@TurboTraveler
Costco is about the only place without 87, from what I’ve seen. I get mine at Kings.

bernardelliots said:
@TurboTraveler
Costco is about the only place without 87, from what I’ve seen. I get mine at Kings.

Gas is like 40-50 cents more at Kings. I don’t shop there enough for any discounts, and it’s crazy because I can drive 10 minutes to 7/11 and get cheaper gas. The manager said prices vary by location, and we’re in a high-income area.

@TurboTraveler
I’ve seen price differences all over, especially from state to state or in wealthier areas. It’s crazy how much prices can change just a few miles away.

@TurboTraveler
Yeah, I get around 50 cents in gas savings from groceries a month, so it’s about the same for me.

I’d go with 87 to be on the safe side since the manual recommends it.

I own a 2024 Telluride. I’ve been using both 85 and 87 octane out of habit from my old cars. I asked the salesman at the dealership what gas I should use, and he said Kia recommends 87, but he hasn’t heard of any issues with 85. That wasn’t very helpful, but after using both, I found 87 gives me better mileage for my 80-mile commute.

@valentinholes
That’s weird, I tried both and didn’t notice any difference.

fatilo said:
@valentinholes
That’s weird, I tried both and didn’t notice any difference.

Same here, I tried both and didn’t get any improvement in mileage.

fatilo said:
@valentinholes
That’s weird, I tried both and didn’t notice any difference.

I got about 1.3 mpg more with 87, but it’s probably not enough to justify the extra cost.

I have a 2024 Telluride and live in Northern Colorado. I only use 87.

In Salt Lake City, we have the same situation. I still prefer 87 because these engines seem to need specific fuel types. You wouldn’t know if something’s wrong until it’s too late unless you’re doing used oil analysis.

85 is fine, but make sure to use top-tier gas like from Costco, Shell, or Chevron.

I use 87 for my 2024 Telluride. My dad used 85 in his 2023 once, and the knocking started immediately. It’s not worth risking your $60k investment just to save a few bucks.

bernardelliots said:
I use 87 for my 2024 Telluride. My dad used 85 in his 2023 once, and the knocking started immediately. It’s not worth risking your $60k investment just to save a few bucks.

What’s your elevation? Up here at 5000+ ft, the oxygen is different, so 85 works instead of 87.

@TurboTraveler
I’m at about 5400 feet at home and commute to downtown Denver regularly.

I’ve been using 85 in Colorado with my Telluride for over 100,000 miles and haven’t had any issues. Obviously, when I’m out of state, I use 87 since it’s standard across the country.